To conclude, perhaps the most important lesson learnt from scalings (REF ) and (REF ) is the universality of the entrainment mechanism.
Given the values of the shear stresses at the virtual contact point (\(\hat{\tau }_{01,\ast }\)  for liquid 1, \(\hat{\tau }_{12,\ast }\)  for liquid 2), the amount of fluid dragged in each film can be readily estimated using the same ideas exposed in the original work of [1]}.
